For example, a contact probe is used for electrically connecting an inspection object such as a semiconductor integrated circuit with an inspection substrate on the side of a measuring apparatus. Under inspection, usually, a socket which supports a plurality of contact probes is fixed to an inspection substrate, and the socket is pressed against an inspection object. At this time, one end of each contact probe is contacted with corresponding electrode of the inspection substrate, and the other end thereof is contacted with corresponding electrode (for example, solder bumps) of the inspection object. In packaged state for shipping or unused state (stored state) of such a socket, in order to protect the tip ends of the contact probes which are projected from the socket, a probe cover is attached to the socket. In the present state of the art, the probe cover is fixed to the socket by screwing. For example, screwing is performed in four to six portions. FIGS. 15 and 16 illustrate a state where a conventional probe cover 801 is screwed to a socket 900 in four portions.